1. Field of the Invention
The present invention relates to a substrate transport apparatus and, more particularly, to an apparatus with multiple arm assemblies on a common axis of rotation.
2. Prior Art
U.S. Pat. No. 5,720,590 discloses an articulated arm transfer device having a drive section with coaxial drive shafts, magnetic driving stators stationarily connected to a frame, and magnetic driven rotors on the shafts. U.S. Pat. Nos. 5,577,879 and 5,765,983 disclose scara arms. Non-coaxial side-by-side dual scara arms are offered for sale by three Japanese companies; the UTW and UTV series of robots by MECS, the RR series of robots by RORZE; and the LTHR, STHR, SPR series of robots by JEL.
In accordance with one embodiment of the present invention a substrate transport apparatus is provided comprising a drive section, two independently movable arm assemblies, and substrate holders. The arm assemblies are connected to the drive section on a common axis of rotation. The substrate holders are connected to the arm assemblies.
In accordance with another embodiment of the present invention, a substrate transport apparatus is provided comprising two independently movable arm assemblies, substrate holders, and a drive section. The substrate holders are connected to the arm assemblies. The drive section has a frame, a pulley rotatably connected to the frame by a first drive, and second and third drives connected to the arm assemblies. The pulley is operably connected to both the two arm assembly by transmission members.
In accordance with another embodiment of the present invention, a substrate transport apparatus drive system is provided comprising a frame, magnetic driving stators, a drive shaft assembly, and a pulley. The stators are stationarily connected to the frame. The drive shaft assembly has at least three coaxial shafts. Each shaft has a magnetic driven section aligned with a separate one of the magnetic drive stators. The pulley is rotatably connected to the frame by one of the shafts.
In accordance with another embodiment of the present invention a substrate transport apparatus is provided comprising N independently movable arm assemblies, substrate holders, and means for independently rotating each of the arm assemblies. Each arm assembly has A axis of rotation about which at least a portion of the arm assembly can rotate. N and A are integers greater than one. The substrate holders are connected to the arm assemblies. The rotating means can rotate the arm assemblies about their respective A axis. The rotating means comprises M motors. M is an integer less than N times the smallest value of A.
In accordance with one method of the present invention a method of moving a substrate transport apparatus is provided comprising steps of providing the apparatus with a frame, a pulley rotatably mounted to the frame, and two arm assemblies rotatably mounted to the frame; rotating the pulley relative to the frame as the two arm assemblies are rotated with the pulley to rotate both arm assemblies in a same direction relative to the frame; and maintaining the pulley in a stationary position on the frame as the two arm assemblies are independently rotated relative to the frame to independently extend and retract the arm assemblies.